Graffiti Wall Critiques

LSC reference:  CM.ex.2.16

Critique 1:  My objection to this, and some of the other activities you have detailed in the exhibit documentation, is that you are emulating a non-electronic technology with electronic means, without really adding any innovation that electronics would make possible.   If graffiti were electronic, why wouldn’t it use computer power to create something akin to moving, or even intelligent, markings?  I’ve created an applet to show you what this might look like:   

http://www.elasticmind.com/squiggle  (just doodle some lines on the wall)

http://www.elasticmind.com/squinch/ (this one has heads)

In other words,  these exhibits should break new ground, and innovate some new means of expression, even as they revisit and re-interpret historical ones?

Critique 2:  The Gyration Mouse is not a 3D input device.  I could be wrong, but the documentation for this device doesn’t state anywhere that it’s tracking 3 dimensions.  Moreover, it’s a “relative” device, like most mice, and thus actually doesn’t record any absolute locations at all, just relative ones.  If they are using a gyroscope to record absolute locations, then I think we’d better tell the U.S. Navy about it right away.  The Gyration Mouse is the functional equivalent of a laser pointer.  The whole point of the Gyration Mouse is to be able to control a large area of screen with small motor movements of the wrist, which is quite different from what the Graffiti artist is doing.

Critique 3: Gyration Mouse may not support more than two devices simultaneously.  It’s unclear from the documentation in the pdf download datasheet for the UltraPro, but the datasheet for their Gyro Remote product GP240-001 

  http://www.gyration.com/files/datasheets/DL00539-001-A%20GP240-001.pdf

states: 

Multi-receiver functionality allows you to install up to

eight remotes, mice and keyboards on one computer,

two of which may be used simultaneously

So it’s worth checking whether three “spray can” transmitters using their rf 49khz signal could be operated at once from a single receiver.  I would also suggest that a device capable of broadcasting 100 feet might cause crosstalk with other rf technologies you might be using in other exhibits.

Note:  There are wireless 3D input devices which do track absolute locations in three (or more) dimensions (degrees of freedom).  The most reliable of these uses ultrasonic signals, along with an IR synch pulse.  A 40 khz sound pulse (inaudible to humans, but perhaps not to dogs) is sent out from the handheld wireless (spray can) transmitter 30 to 60 times a second.  Three or more receivers behind the graffiti wall receive each pulse and clock the time it took for the sound pulse (in milliseconds) to reach each receiver.  The IR synch pulse is effectively instantaneous since it travels at the speed of light, much faster than the speed of sound.  The three elapsed times establish the position of the spray can transmitter by simple triangulation, and the high frequency of the pulse rate gives the realtime feeling.  Again, there might be some issues with crosstalk from more than one transmitter, however this could be overcome by tuning each of the transmitters to a slightly different frequency, or by multiplexing (interleaving) the pulses from each transmitter.   It’s also possible to track 3D locations using video, but this introduces a host of other problems.

So in sum, since the Gyration Mouse is basically a pointer, I don’t see how you are going to use it to emulate the effect of broad arm movements of a real spray can on a wall, and I don’t see how you can use it to emulate the spray size which would be effected by moving the can closer or farther away from the wall..